Typewriter device



M. EDMUNDSON.

TYPEWRITER DEVICE.

APPLICATION FILED FEB. 26, 1920. 1,382,417. Patented June 21, 1921.

Fgivl' mun/r01? Arramva'va.

UNITED STATE PTENT OFFIE..

TYPEYVRITER DEVICE.

Specification of Letters Patent.

Patented June 21, 1921.

Application filed February 26, 1920. Serial No. 361,433.

To all whom, it may concern Be it known that I, MILLARD EDMUNDSON, a citizen of the United States, and a resident of the city and county of San Francisco, State of'California, have invented new and useful Improvements in Typewriter Devices, of which the following is a specification.

My invention has for its object the provision of a relatively hard surface for mounting on the platen of a typewriter, or the like, whereby impressions may be made simultaneously on a plurality of superposed sheets against the said hard surface, as a backing, thereby securing a greater number of clearer copies than heretofore attainable where the relatively yielding surface of the platen only served to back the sheets. Moreover, this hard surface is provided in the shape of a spring sheet axially parted in one or more places so that it may be readily placed over or removed from the platen with the greatest ease and without removing or changing any of the typewriter parts.

Other objects will appear from the drawings and description.

These objects I accomplish by forming a cylindrical shell, preferably of a plurality .of members of thin spring metal, and of such dimensions and formed to such a curvature that the edges just meet, or are feathered to slightly overlap so that when assembled in place on the platen form a true cylindrical surface against which the type impressions are received.

By referring to the accompanying drawm s my invention will be made clear.

igure 1 shows the platen of any well known form of typewriter, the balance of the machine being well known and not shown, and having assembled thereon a thin plate cover, or shell, which is the subject of my invention.

Fig. 2 shows in perspective the platen with a pair of cooperating plates of spring metal ready to be sprung into place in assembled position on the platen, and which when assembled will appear as shown in Fig. 1.

Fig. 3 is a detail of one end of the platen with the shell assembled thereon. and showing a holding means for the plates which in some instances will prove advantageous.

Fig. 4 is an end view of Fig. 3.

Throughout the figures the same numerals refer to identical parts.

A platen of any well known form of type- Writer is shown by the numeral 1, and which is mounted to turn upon an axis 2, 2, and is provided with the usual ratchet, or other operating connections as 3. Numerals 4, 5 show two plates which together form the surface of a true cylinder when snugly fitted in place on the platen 1.

In some instances spring the partially cylindrical spring ring 6 over the plates 4c, 5 when they are in place, and a similar ring at the opposite end, to better secure them, although when they are properly formed to exactly and snugly fit the platens this will not usually be necessary.

The edges of the plates 4: and 5, as shown at 9 and 10 respectively, may advantageously be out on an angle to the axis, and the opposite edges as 11 and 12 formed parallel to 9 and 10 respectively, so that the plate 4: will embrace at the right hand end slightly less than half of the surface of the platen 1, and at the opposite end will embrace slightly more than half of the said surface; whereas the plate 5 will embrace slightly more than the half surface of the platen 1 at the right hand end and slightly less at the left hand end, the sum of the circular periphery of the two plates at each end, however, being the periphery of the circle of the platen. It will then be seen that in order to adjust the exact diameter of the circle formed by the cooperating plates to that of the platen, it will only be necessary to slide the plates in the direction of the arrows 7 and 8 in order to slightly increase the diameter, or, in the opposite direction to slightly decrease the diameter. The variations in the diameters of various platens are but a few thousandths of an inch in any given size,

and therefore my two plates 4: and 5 may be made as an article of manufacture, and by the slight relative movement in the direction of the arrows 7 and 8 may readily adjust themselves to any commercial platen. Or, one or both of the edges 9, 10, 11, 12 may be feathered so that the plates may overlap sli htly along the line of jointure, in which case the line of the joint may be parallel with the axis.

The operation is as follows:

In practical work on a typewriter the platen surface is made relatively soft so as not to injure the faces of the type, and when one or two sheets of paper are used, to provide a yielding surface so that the entire surface of the type face will make a clear impression because a certain portion of the it may be advisable to sink slightly in the yielding portion of the platen until the ed es of the type make a suitable impression. owever, when a number of sheets are employed together with carbon paper for the purpose type facing will of making a plurality of impressions the built upplurality of sheets and carbon paper provide a suitable cushion or yielding surface for the type, and the harder surface of my invention may advantageously be employed on the platen to secure a clearer impression of the type on the plurality of copies. When such is desired the operator springs the plate 4 in placeon the platen and then springs sheet 5 in place on the opposite half of the platen, and if they are provided with feather edges the latter may be set in such a position that they will slightly overlap; or, if provided with the angular edges, as shown in the figures, the plate 4: is tobe set relatively to the left of plate 5 and the two plates moved in the direction of the arrows 7 and 8 until the edges exactly meet when a complete and accurate hard surface will be snugly completed and will adhere in position on the surface of the platen.

If the plates 4 and 5 are not made of material having a sufficient spring, holding the surface having proximate edges on a line angular with the platen. axis, whereby relative axial movement of the surfaces will vary the inclosing cylindrical'diameter, as

and for the purposes set forth.

In testimony whereof, I have hereunto set my hand at San Francisco, California, this 21st day of February, 1920.

MILLARD EDMUNDSON. j 

